<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style type="text/css">
        /* class选择器 */
        .box{
            background-color: rgb(31, 188, 115);
            height: 60px;
            width: 60px;
        }
        /* id选择器 */
        #box2{
            background-color: rgb(255, 0, 98);
            height: 150px;
            width: 150px;
        }
    </style>
</head>
<body>
    <div style="width: 220px;height: 220px;background-color: blueviolet;">
        <div id="box2"/>
        <div class="box"/>
</body>
</html>